In recent years, as a light source for the projection display apparatus, attention has been focused on a solid-state light source such as a LED (light-emitting device) or a semiconductor laser. The projection display apparatus equipped with the solid-state light source includes an illumination optical system that includes a solid-state light source and an optical element configured to guide light emitted from the solid-state light source, an image forming element configured to modulate the light guided by the illumination optical system, and a projection optical system configured to project the light modulated by the image forming element.
The light emission efficiency of the solid-state light source has been improved year by year. For example, even a LED having light emission efficiency exceeding 150[lm/W] is known. However, for a light source of the projection display apparatus required to project a high-luminance image, not only the light emission efficiency but also a light emission amount are important factors.
In this regard, even when one LED module each is prepared for each of the respective colors R, Q, and B, the sum of the amount of light emitted by these three LED modules cannot reach the amount of light emitted by a conventional discharge lamp. A LED module (may be referred to as “high power LED”) having power consumption exceeding several tens W is also known. However, even when one high power LED module each is prepared for each of the respective colors R, G, and B, the sum of the amount of light emitted by these three high power LED modules cannot reach the amount of light emitted by the conventional discharge lamp.
Thus, by preparing a plurality of LED modules for each of the R, G, and B colors, the sum of light emission efficiencies may be increased.